Details

Autor(en) / Beteiligte

• Hagan, Martin
• Pankov, Genady
• Gallegos-Monterrosa, Ramses
• Williams, David J.
• Earl, Christopher
• Buchanan, Grant
• Hunter, William N.
• Coulthurst, Sarah J.

Titel

Rhs NADase effectors and their immunity proteins are exchangeable mediators of inter-bacterial competition in Serratia

Ist Teil von

• Nature communications, 2023-09, Vol.14 (1), p.6061-6061, Article 6061

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2023

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Many bacterial species use Type VI secretion systems (T6SSs) to deliver anti-bacterial effector proteins into neighbouring bacterial cells, representing an important mechanism of inter-bacterial competition. Specific immunity proteins protect bacteria from the toxic action of their own effectors, whilst orphan immunity proteins without a cognate effector may provide protection against incoming effectors from non-self competitors. T6SS-dependent Rhs effectors contain a variable C-terminal toxin domain (CT), with the cognate immunity protein encoded immediately downstream of the effector. Here, we demonstrate that Rhs1 effectors from two strains of Serratia marcescens , the model strain Db10 and clinical isolate SJC1036, possess distinct CTs which both display NAD(P) + glycohydrolase activity but belong to different subgroups of NADase from each other and other T6SS-associated NADases. Comparative structural analysis identifies conserved functions required for NADase activity and reveals that unrelated NADase immunity proteins utilise a common mechanism of effector inhibition. By replicating a natural recombination event, we show successful functional exchange of CTs and demonstrate that Db10 encodes an orphan immunity protein which provides protection against T6SS-delivered SJC1036 NADase. Our findings highlight the flexible use of Rhs effectors and orphan immunity proteins during inter-strain competition and the repeated adoption of NADase toxins as weapons against bacterial cells. Rhs proteins delivered by the Type VI secretion system play a key role in competition between rival bacteria. Here, the authors show that Rhs proteins with exchangeable NAD(P) + glycohydrolase toxin domains and ‘orphan’ immunity proteins are flexible agents of intraspecies competition in Serratia .